Protecting mercury-vapor apparatus.



0. 0. KRUH.

PROTECTING MERCURY VAPOR APPARATUS.

APPLIOATION rum) SEPT. 20, 1901.

1,076,21 2, Patented 001;. 21, 1913 Q Fig.1.

Mgfnesses: Inventor 2 :5,; Osias O.Kruh. w by UNITED STATES PATENT OFFICE.

osms o. KRUI'IJOF soimmeo mny, NEW YORK, asexonon e10 GENERAL ELECTRIC comrmwga CORPORATIUN\0F NEW stoma -=BRO'1-EOTING MERCURY-VAPOR APPARATUS.

Specification ofLetters- Patent.

Patented Oct. 21, 1913.

a lication filed septernbcr 20,1907. "seriarnoi 393315.

To all whom it may concern:

Be it'knovvn'thatI, Osms 0. Kane, a subject of the Emperor of Austria-Hungary, residing at Schenectady, in'the county of Schenectady and State of New York, have invented certain new and useful Improvements in Protecting Mercury-Vapor Apparatus, of which thefollowin'g is a specification.

Tn'the operation (if high voltagemercu'ry for supplying constant current circuits containing are lamps in series, thestarting'of the rectifier is usu'allyeit'ecteldby means'o'f starting anodes, 'or'dirra'rily of me'r'cur arranged adjacent to the cathode. 'hese starting anodes, after th'eapparatus is once put into operation, are not'usuaily continued in operation. 'i/Vhen'such a system'isworlting it has been observed that high potential discharges sometimes occur ibet ween the cathode and 'the starting anodes. It then frequently happens that the cathode spot, or in other Words, thep'oint'on themain cathode from which the main rectifier are emanates, shifts over fromthe cathodeto one of the starting anodes. The main arc current therefore passes through this ano'de and may cause more or less considerable overheating of the corresponding parts of boiled away and the glass fractured. Also it sometimes happens that. the highvoitage discharge between the cathode and the anodes is so severe as actually't-o puncturethe glass of the rectifier tube.

The high voltage appearing between the starting anodesand the cathode appears to be due to oscillations or high frequency effects caused by the interaction of the capacity and inductance of the system With'its arc lighting load. I have found that the shifting of the cathode s' ots and its attendant evils, ail of which appear to be caused in one way or another by the high potentials produced in the neighborhood of the cathode and the starting anode,'ma v be obviated by surrounding the cathode and the starting anodes by shells of "metal or other good electrically conducting material. This arrangement neutralizes any tendency for the cathodespbt' to jump'toone (if the starting anodes, and it' also prevents the building up of any high difference in potential between the cathode and one of the starting anodes, and so a'voidsany danger of puncture of the glass'by ahigh potential discharge between theseiparts.

The novel features which characterize 'my invention Ihave endeavoredto point Out'i'n the appended claims. The'invention itself, as embodied 'in practice, -will perhaps be better unlderstoo'd'by'refrence to thetfollowin; desert'tion takeninconnectionwiththe ac ompa'n'ymg "drawings; in which I Figure '1 shows a' system embodyingfmy invention; and FigQZ a modifiedfon'n of protecting device. I

In "Fig. "-1 the source ot supply forthe rectifier system 'th'e'rein indicated is shown as consisting ofa constant current transformer havin a primary coil "1 "an'd a secondary coiL-Q, 'mo'vatte with respect 'to'the rimary. The transformer ma be of an tion. The'secentiarvwinding with 'three'taps connectetifto 'niaihs 3 and 5. Mains 3 and "5 which eittend to the rectifier a's'will be described, ar cohneeted is provided 8 are provided inwt'iiich' liemain"anddes'9 and 10 are located. At the bottom tifthe rectifier tube are three potikts 'filled "with mercury to constitute three electrodes 151,312 and 13 int'h'e usual'wa' Themidtile'body 12, forms the cathode of the rectifier while the'mercury in the pockets 11 and'iBco'nstitutes the starting anodes.

The load circuit indicated by a series (if ar'c lamps at .Mis connected toth'em'ain 4 at me end and to the 'cat-hode12a't'the other. A1. inductance coil '15 in series "with this load circuit serves'tosinooth thecurrent'and to-steadythe operation of the system.

Current for the starting anodes i i and 1'3 is sup lied'from a constantpotenti'al sonr'ce offmoderatc voltage, such for-example as the small step-down transformer 16. The outer terminals ofjthe secondary '17 'df'tiiis transformer are connected, as indicated tb the starting electrodes 11and 13. 'whiiethe circuits of the rectifier tureof a short-circuited secondary to op-,

through inductance 18 to the cathode 12. By shaking the rectifier tube 6 mercury is caused to flow temporarily between the cathode and one or more of the starting anodes and thus initiates the starting arcs in a manner well understood. The main roper, if not alreadyclosed, may then e closed and the starting arcs from the cathode will cause the main arcs in the rectifier to start. The apparatus being thus started into operation it may happen that from various causes,

some of which are more or less obscure, high voltages are produced between the cathode 12 and the anodes 11 and 13, as described, so

that discharges sometimes occur from thecathode 12 to one or the other of the anodes -11 and 13. When this happens a new cathode spot is frequently or generally produced at the surface of the starting anode and the main cathode spot immediately shifts over to the new cathode spot in the starting anode, with results which may in some cases be disastrous to the tube. I have found that all this may be prevented by surrounding the region of the cathode and the starting anodes by electrical circuits of good conductivity, such, for example, as the closed circuits 19 of sheet metal, such as copper. This member 19 may consist for example, of tinfoil surrounding the glass portion of the tube immediately overthe cathode and the starting anodes, but out of connection with the leading-in conductors, or it may consist of heavier sheet metal formed. into a shell surrounding the respective electrode chambers. f

Instead of metal in sheet form used for the purpose indicated, I mayin some cases simply twist wire about the electrode-conin Fig. 2. In this case the wire is simply interlaced around the three legs and twisted together. a

It is possible that the metal surrounding the electrode chambers operates in the naose or damp out the oscillations or high requency effects which tend to roduce discharges from the cathode to t e adjacent anode. There is reason, however, for think; ing that the trouble described is due to an accumulation of high otential charges pn the surface of the recti er tube in the vic ityof the electrodes in question. The pres ence of metal electrically connecting these regions therefore, serves to equalize the static charges and so prevents the jumping of current from the cathode'to a starting anode. Whatever, however, may be the true explanation of the reasons for the shifting of the cathode spot, I have found that the trouble may be prevented by the means indicated. Therefore, while I have given my frequency effects.

1 ,cvae 1 2 my invention, I do not wishto be limited "to any particular theory since the beneficial effects of my invention may be obtained, re-

gardless of what view may be entertained "trical contact therewith.

2. In a vapor electric device, the combination of an exhausted tube havingna cathode, a starting anode located adjacent thereto, and means for preventing the cathode spot from shifting to said anode by mail izing the static stress between said cat ode and anode.

3. In a mercury vapor rectifyin apparatus, the combination of a rect er tube having main operating electrodes and start ing electrodes, and electrically conduct-ing circuitsin proximity to the main negative electrode :and the starting electrodes for preventing the shifting of the cathode spot from the negative electrode to either of the starting electrodes.

4. In amercury vapor apparatus, the combination of an evacuated tube, a ne 9.- tive electrode, an auxiliary or startin e ectrode electrically connected therewit during the operation of said apparatus, and means adjacent to said negative electrode for preventing abnormal electrical discharges between the cathode and starting electrode to prevent the starting electrode from eratingas a negative electrode to the exclusion of said'negative electrode.

5. In a mercury vapor device, the combination of a main anode and a cooperatin cathode, a starting anode having a ten ency to operate as a sustained cathode by the shifting of the arc to the startin anode from the regularly operating catho e, and

inductive means ,external to said cathode for restraining that tendency. I

6. In a vapor electric device, the combination of an exhausted tube having a cathode, a starting anode located adjacent thereto, and a closed circuit of low resistance for equalizing the static stress between said cathodi and anode by damping outhigh 7. In a vapor electric device, the combination of an, exhausted tube having a cathode, starting anodes adjacent thereto, current'supply wires for said device, and a conductor insulated from said wires and form ing a closed circuit of low resistance in inductive relationto said cathode and anodes.

8. The combination of a source of high present understanding of the operation of potential current, a vapor electric device iao having a cathode, a main anode or anodes and a starting anode electrically connected to said source and means for preventing disturbing electrical conditions at the cathode and starting anode which would tend to cause the latter to become a sustained cathode.

9. The combination of a high potential transformer, a vapor electric device connected thereto having main cooperating electrodes and a starting electrode electrically connected to the cathode throi'igh an inductive path of relatively low resistance, and electrically conducting circuits in proximity to the main negative electrode and the starting electrode for preventing disturbances tending to cause the starting electrode to operate as a sustained cathode.

10. A current rectifying device comprising a mercury containing receptacle of insulating material, and a band of conducting material on the exterior thereof, said band being independent of the circuits of the device.

In Witness whereof, I have hereunto set my hand this 18th (lay of September, 1907.

OSIAS ()v KRUH. \Vitnesses BENJAMIN B. HULL, HELEN ORFORD. 

